The present invention relates to front-opening interface mechanical standard (FIMS) system equipment and, in particular, to a FIMS transport box load interface that facilitates proper registration and accurate, secure positioning of a transport box as the specimens it contains are transferred between a minienvironment and a separate, enclosed specimen transport system.
A system designed to incorporate FIMS permits handling of semiconductor wafers inside and outside of clean room facilities by interfacing a clean semiconductor wafer cassette transport box or pod to a clean environmental housing for semiconductor processing equipment or to other clean environments. The system concept entails mating a box door on a front-opening unified pod (FOUP) or cassette container box to a port door on an equipment enclosure and transferring the cassette into and out of the processing equipment without exposing to outside contamination the semiconductor wafers carried by the pod or wafer cassette.
A standard interface is required for cassette transport boxes intended to control the transport environment of cassettes containing semiconductor wafers. The standard interface addresses the proper transport box orientation for material transfer and maintains continuity between the transport box and semiconductor processing equipment environment to control particulate matter. The FIMS specifications are set out in the Semiconductor Equipment and Materials International (SEMI) standard SEMI E47-, E57-, E62-, and E63-0298 (1996-1998).
A FIMS system includes minimum volume, sealed front-opening boxes used for storing and transporting semiconductor wafer cassettes and canopies placed over wafer processing areas of semiconductor processing equipment so that the environments inside the boxes and canopies in cooperation with clean air sources become miniature clean spaces. The boxes are made of plastic materials having registration features located relative to one another within and of sizes characterized by relatively wide tolerances that can affect equipment alignment precision. What is needed is a box load interface implemented as part of a transfer mechanism for precise box alignment during loading and unloading of wafer cassettes from a sealed box without external environment contamination of the wafers carried by the wafer cassette.
The present invention is a box load interface implemented in a FIMS system. The box load interface comprises a retractable port door that is attachable to the box door of a transport box and that selectively moves the box door toward or away from the box cover of the transport box to thereby open or close it. A port plate has a front surface and a port plate aperture through which the box door can move as the port door moves the box door toward or away from the box cover. A slidable tray slidably mounted to a support shelf positioned transversely of the port plate receives the transport box in a predetermined orientation established by kinematic coupling surfaces located on the top surface of the slidable tray.
A slidable tray positioning mechanism selectively moves the slidable tray on the support shelf and thereby moves the transport box toward or away from the port plate. There are three preferred embodiments of a box hold down clamping mechanism mounted to the support shelf. The positioning mechanism is operatively connected to a first embodiment of the clamping mechanism to engage the clamping mechanism to a front clamping feature positioned on the bottom surface of the transport box and thereby apply an urging force to the box cover against the kinematic coupling surfaces while the slidable tray advances toward the port plate to push the front opening of the box cover against the front surface of the port plate. The positioning mechanism is operatively connected to the clamping mechanism also to disengage the clamping mechanism from the front clamping feature and thereby release the urging force from the box cover against the kinematic coupling surfaces while the slidable tray retracts from the port plate to pull the box cover away from the front surface of the port plate.
The box hold down clamping mechanism preferably includes a pivot finger pivotally mounted to the support shelf, and the slidable tray includes a push pin. The pivot finger has a recessed area that forms first and second angularly offset push pin contact surfaces that receive the push pin as the slidable tray moves the transport box toward the port plate and thereby rotates the pivot finger in a first rotational sense to engage the pivot finger to the front feature and moves the transport box away from the port plate and thereby rotates the pivot finger in a second rotational sense that is opposite to the first rotational sense to disengage the pivot finger from the front feature. The pivot finger includes a roller bearing that engages the front feature as the pivot finger rotates in the first rotational sense.
The positioning mechanism and each of second and third embodiments of the clamping mechanism are fixed with respect to each other so that a clamping mechanism operating under fluidic control engages and disengages from the front clamping feature in the absence of force applied by the sliding motion of the slidable tray.
The port plate includes a surface from which two compliant latch keys extend to mate with and operate the latch actuating coupler mechanism within its relatively wide alignment tolerance range, and a latching motor mechanism operatively connected to the compliant latch keys selectively rotates them between first and second angular positions. The latch keys are designed to xe2x80x9cwobblexe2x80x9d laterally to accommodate the tolerance range of the corresponding mating features on the box door and thereby ensure proper alignment to it. The first angular position secures the port door to and the second angular position releases the port door from the box door when the port and box doors are in matable connection.
An alternative embodiment of the two compliant latch keys includes a latch key pull back mechanism operating under fluidic control to securely hold the box door in alignment against the port door when the box and port doors are in matable connection. Maintaining the alignment established to fit the port door latch keys into the box door mating features ensures that there is no post-separation alignment shift between the box door and port door resulting from the loose tolerance range necessitating the wobbly latch key design.
The box load interface system also comprises a port door translation mechanism that is operatively connected to the port door to advance it in a forward direction toward the port plate aperture to attach the port door to the box door and then retract it and the attached box door in reverse direction away from the box cover and through the port plate aperture. A port door elevator assembly operates in cooperation with the port door translation mechanism to move the port door in a direction generally parallel to the front surface of the port plate after the box door has been moved away from the box cover and through the port plate aperture.
In a first embodiment, the port door translation mechanism and the port door elevator assembly are independent systems operating under coordinated control of separate motor drive assemblies. In a second embodiment, the port door translation mechanism and the port door elevator assembly are combined as a unitary mechanism. The unitary mechanism is implemented with a pivot link structure operating under control of a motor-driven lead screw mechanism to move the port door sequentially in transverse directions of movement that are the same as those accomplished by the translation mechanism and the elevator assembly of the first embodiment.
The transport box holds a container in which multiple wafer specimens are stored in spaced-apart, stacked arrangement. The container has an open front side from which the specimens are removed or into which the specimens are inserted. The box load interface comprises a differential optical scanning assembly for detecting positions of the wafer specimens. The scanning assembly scans the wafer specimens in a direction parallel to a facial datum plane, which is defined as a vertical plane that bisects the wafer specimens and is parallel to the open front side where the wafer specimens are removed or inserted. Scanning assembly includes two spaced-apart, pivotally mounted scanner fingers that are operable to center and push back dislodged specimens before determining their orientations in the cassette.
A robot assembly is supported by a linear traveling assembly between adjacent port plate apertures for removing and inserting wafer specimens from the transport box. The linear traveling assembly includes a nut mechanism contained within a housing secured to a carriage that supports the robot assembly. The carriage travels along a lead screw between the port plate apertures and is driven by the nut mechanism that includes a lead nut threadably engaged with the lead screw and rotated by a drive motor through a belt and pulley arrangement.
Additional objects and advantages of this invention will be apparent from the following detailed description of preferred embodiments thereof, which proceeds with reference to the accompanying drawings.